A conductive composition containing a conductive metal as a main component has been widely used for achieving an electrical conduction in the field of electronic materials and the like. For example, the conductive composition may be used for forming a circuit of a printed wiring board, a lead-out wiring of a touch panel, an electrical junction, etc. This conductive composition is a fluid formulation, and typical examples thereof include silver pastes. The conductive composition is applied in a pattern by screen printing, ink-jet printing (hereinafter referred to as IJ printing), or the like, and the applied composition is hardened by applying a light or heat to form a conductive hardened product. The conductive composition contains a conductive metal filler, and silver is often used in the filler because it has an excellent oxidation resistance and a low specific volume resistance. However, the silver is costly, and often causes migration, disadvantageously. Therefore, use of copper in the conductive composition has been studied in recent years, because the copper has a low specific volume resistance (low next to the silver), is inexpensive, and has an excellent migration resistance.
As a copper filler for the conductive composition, Patent Publication 1 discloses a copper particle coated with an aliphatic monocarboxylic acid for improving the oxidation resistance and dispersibility. Furthermore, Patent Publication 1 describes that when the copper particle is coated with the aliphatic monocarboxylic acid by a wet method, and is then dried and pulverized by using a wind circulator, the resultant coated copper particle can exhibit a high dispersibility and an excellent effect of controlling the viscosity of the conductive composition.